On July 11, before the London Olympics were even under way, controversy erupted at the Olympic Park’s fish-and-chips shops. Some park workers wanted to buy chips without fish, but staff members couldn’t serve them. After enduring vociferous complaints from hungry customers, one stall hung up an explanatory sign. It said that “due to sponsorship obligations with McDonald’s,” the stand was not allowed to sell french fries sans fish. For that, workers and spectators would have to head to one of the four McDonald’s restaurants in the Park.

“Chip-gate,” as the situation came to be called, gave the British press something to bite on. It was “the moment that corporate sponsorship finally lost its mind,” blogged the Daily Telegraph‘s Tom Chivers, dubbing McDonald’s “the official Greasy Potato Snack of London 2012.” Some critics question whether the Olympics should accept backing from Big Food. “At an event that celebrates athletic achievement, I don’t think we need to promote high-calorie, high-fat foods that are not good for the health of the human body,” says Terence Stephenson, a practicing pediatrician and chair of the Academy of Medical Royal Colleges, which represents 200,000 U.K. health professionals.

The walls of the bridge leading into the Olympic Park are decorated with scenes from the Olympic-torch relay intertwined with images of Coca-Cola bottles. Olympic mascot figurines, made by “official Olympic treats provider” Cadbury, can be found at every official Olympic store. And the only beer on tap at Olympic venues is Heineken. In fact, all branded food and drink served at the Olympics will come from just five companies: McDonald’s, Coca-Cola, Cadbury, Heineken and granola-bar maker Nature Valley.

The pairings may seem incongruous. With the exception of some endurance athletes, who burn 4,000 to 6,000 calories every day in training, fast food, alcohol and sugary snacks are generally off the menu for Olympians. Popular U.S. swimmer Ryan Lochte credits his abolition of fat and sugar (including his favored breakfast, the Egg McMuffin) from his diet with helping to push him to the top of the podium. Team GB’s Jenna Randall, a synchronized swimmer, says she foreswears even a bite of chocolate. Yet spectators at London 2012 venues, whose Olympic exertion involves trudging from stadium to food stand, are offered a burger, candy and beer buffet officially sanctioned by the Olympic brand.

Unsurprisingly, the arrangement has come under criticism from health experts and campaigners. Malcolm Clark, head of the U.K. Children’s Food Campaign, worries that young visitors are being targeted. “The Olympic mascots are promoting chocolate sweets and Happy Meals,” he says, pointing out that Wenlock and Mandeville were designed to appeal to 5-to-15-year-olds. “What kind of signals is this sending?”

In July, International Olympic Committee (IOC) president Jacques Rogge said there was a “question mark” over continuing involvement with McDonald’s and Coca-Cola, which have sponsored the Games since 1976 and 1928, respectively. “For those companies, we’ve said to them, ‘Listen, there is an issue in terms of the growing trend on obesity — what are you going to do about that?’ ” he told the Financial Times. He later e-mailed a statement to Reuters:

I would like to clarify comments attributed to me in several media reports regarding Coca-Cola’s and McDonald’s Olympic sponsorship. The IOC hugely values the long-term sponsorship and support of both McDonald’s and Coca-Cola. Through the years we have personally witnessed the positive impact that they make as TOP sponsors.”

McDonald’s, which has paid about $100 million for the publicity and goodwill it hopes its participation will generate, is working to forestall further criticism. On July 26, McDonald’s held a press event at its flagship Olympic Park restaurant. Journalists were greeted at the door by a willowy waitress offering bottled water and fruit smoothies. Posters of fruit and vegetable snacks brightened the room, while next to the speaking podium, an entire Carmen Miranda headdress of bananas, pineapples and grapes appeared to have been disgorged onto a table. With not a Chicken McNugget or french fry in sight, McDonald’s CEO Don Thompson enthused about the chain’s healthy Happy Meal snacks, including his own favorite: kiwi on a stick. “It sounds a little strange, but you’ve got to try it,” he said. “It’s wonderful.”

Organizers argue that the Games simply couldn’t go on without corporate help, a point driven home by a series of Olympic Committee posters on the London Underground. Without McDonald’s, Coca-Cola and others, they read, “there would be no goosebumps, gasps, records smashed, strangers hugged, or a whole world brought together.”

It’s an argument that doesn’t wash with health campaigners, however. A report released on July 26 by the Children’s Food Campaign estimates that less than 10% of the funding for the London Games comes from corporate sponsorship, and it makes up only 2% of the IOC’s total income. “You could easily cut down on the cost of the Olympics by not sending as many IOC officials to stay in swanky hotels,” says Clark. Stephenson agrees that, for the sake of public health, fat must be trimmed from somewhere, even if it means a bit of sacrifice. “If the Olympics can’t continue in its present form without extracting money from companies that sell unhealthy products, then it has become too bloated and needs to look for a different business model,” he explains. “Fewer events, fewer freebies. It needs to be slimmed down.”